Electric photographic flash lamp



Nov. 18, 1958 R. WESTRA ELECTRIC PHOTOGRAPHIC FLASH LAMP Filed June 18, 1956 FIG 2 INVENTOR I REINDER WESTRA United States Patent ELECTRIC PHOTOGRAIHIC FLASH LAMP Reinder Westra, 'Eindhoven, Netherlands, assignor, by mesne assignments, to North American Philips Company, Inc., New York, N.-Y., a corporation of Delaware . Application June 18, 1956, Serial No. 592,050 Claims priority, application Netherlands June 17, 1955 i 3 Claims. (Cl. 67-31) of the neck of the bulb and the exhausttube. An important advantage of the glass base construction is the marked savings in cost as opposed to the metallic base. In addition, the glass base flash lamp can be readily replaced in a lamp holder.

However, the comparatively low cost of a glass base flash lamps may be even further reduced if the cost of manufacture of these items is reduced. Accordingly, the principal object of the present invention to reduce the cost of manufacturing glass base flash lamps. In order to achieve the aforesaid object it is important in the manufacture of such lamps to utilize as much as possible component parts belonging to the normal products of glass works.

In accordance with the present invention a flash lamp having a glass base is provided with at least two axial flat adapting surfaces.

The current supply members of the bead stem carrying the igniting mechanism are located between the sealed edges of the neck of the lamp and the exhaust tube. Moreover, the distance between each axial adapting surface and the axis of the bulb is substantially equal to the distance between each of the lead-in areas of the current supply members in the bulb and the axis of the bulb. The above enables the flash lamp to be inserted in two predetermined positions of the lamp in the holder as well as facilitating the insertion of the bulb in the holder.

The construction herein above described affords the advantage that in the manufacture of the bulbs use may be made of an exhaust tube of the circular cross-section which is a standard tool or product of tube glass factories. The shape of the lamp according to the invention avoids a break in continuity in the profile of-the lamp thereby simplifying the manufacture of said lamps.

In order that the invention may be readily carried into effect one embodiment will now be described, by way of example, with reference to the accompanying drawing in which:

Fig. 1 is a perspective view of a flash bulb according to the invention,

Fig. 2 is a perspective view on an enlarged scale of the shape of the neck of the bulb and the exhaust tube to be sealed therewith. and,

Fig. 3 is a plan view of the lamp base in an associated holder.

Referring to the drawing, the flash bulb or lamp shown .in Fig. 1 comprises a bulb 1 having a neck 2 which is integral with the bulb. By means of a sealing edge 3 the .cylindrical exhaust tube 4 is sealed on the neck 2, of which z-tube only the portion shown, which is more or less coni- Patented Nov. 18, 1958 ice cal in shape, remains after the bulb has been exhausted and the exhaust tube is fused to sealing edge 3 of tube 1. It should be noted that through the exhaust tube the bulb is evacuated and filled with gas and finally the exhaust tube sealed off. In the interior of the bulb are currentsupply wires 5 and 6 which are connected together by means of a glass bead 7.

The current-supply wires 5 and 6,carry a thin wire 8, on which the so-called ignition. paste is provided. When a voltage is applied to the current-supply wires, the wire 8 is brought to incandescence and the ignition paste present thereon assumes a temperature such that the actinically-reacting material 9 present in the bulb 1, which is in the form of, for example, a strip or a wire is ignited. This combustion takes place as a result of the fact that the bulb is filled with oxygen.

In the manufacture of the bulb, the bead stem with the extremities 5a and 6a shown in dotted lines of the current-supply wires 5 and 6 and before the exhaust tube 4 is provided is bent over the circular edge 3 of the aperture in the bulb. Subsequently, the extremities 5a and 6a of the current-supply wires 5 and 6 are bent against the neck 2 of the bulb into the positions 5b and 6b and fixed in position on the neck of the bulb by means of a small flat ring 10 of insulating material, for example, cardboard. The ring 10 is preferably secured to the neck 2 of the bulb by means of an adhesive and, during the use of the lamp, also serves as a limiting member for limiting axial movement of the bulb in an associated holder. Subsequently, the exhaust tube is sealed in position on the edge of the bulb and the further operations referred to above are carried out so that a bulb of the type shown in Fig. 1 is obtained.

The shape of the neck of the bulb may be seen more fully from Fig. 2. This shape of the neck makes it possible to utilize an exhaust tube of circular cross-section despite the presence of the flattened portions 15 and 16 on the neck of the bulb.

In this connection, reference is first made to Fig. 3. This figure shows that the exhaust tube 4 is connected through the circular sealing edge 3 to the slightly conical portion 11 of the neck of the bulb. This portion merges at the imaginary line 12 into a rectilinear portion 13, the generatrix of which is parallel to the axis XX of the bulb. The portion 13 merges at the imaginary line 14 into the bulb 1 proper. The portion 13 of the neck is provided with parallel adapting surfaces 15 and 16 which may also be seen in Fig. 3. These adapting surfaces are likewise parallel to the axis XX of the bulb. Due to the use of conical portion 11, it is now possible to utilize an exhaust tube 4 of circular cross-section at the portion 3 of the neck, which as may clearly be seen from Fig. 3 has a greatly flattened shape. The boundary lines of the adapting surfaces 15 and 16 themselves on the conical portion 11 are lines of a more or less V-shaped form. In Fig. 2,'these lines are indicated by 15a, 15b in full lines, and 16a, 16b in dotted lines, respectively. The peaks of these V-shaped lines are located at A and B on the circular edge 3 of the neck of the bulb. The parts 15c and 16c present on the conical portion 11 also extend fully in parallel with the axis XX of the bulb, at least before the exhaust tube 4 has been sealed with the neck 2 of the bulb.

Fig. 3 illustrates, in what manner the flattened bulb base fits into a holder. This holder is provided with a flattened inlet aperture 20, the flat boundary surfaces 15 and 16 engaging correspondingly shaped parts of insulating material, While the bent extremities 5b and 6b of the current-supply wires bear against low-shaped contact members 21 and 22 provided in the holder.

While I have shown and described the preferred embodiment of my invention, it will be understood that the latter may be embodied otherwise than as herein specifically illustrated or described and thatin the illustrated embodiment certain changes in the details of construction and in the arrangement of parts may be made without departing from the underlying idea ;or,principleofzth'e invention within the:seope of thezappendedclairns.

' Whatis claimed, is:

,,1.-.An,electric1 fiashrbulb having a glass zbaseconstitutedby a1 .substanti'allyzcircular; necktof the bulb..and,.an exhaust 1 tube, :sealed :,=therewith .comprising an :ignition mechanism, a plurality of current supply wires electrically connected .to;said;'ignition mechanism and having part thereof located t'between;the zsealed ..edges .of .the neck .of the bulb and theexhaust itubetandianother' part thereof located eadjacentuto ,a portion ;of the outer periphery.;of said neck, said-:neck,ofathe'bulb being provided with at least one flatraxials surface theadistance between the flat axial surface a'nditheaxis;of1the:bulb being substantially equal: to thetdistance between each .of the lead-in current supply wires and the axis of the abulb.

2. Anelectricpflash .bulb having, a glass base constitutediby asubstantially circular neck of the bulb and an exhaust .tube sealed. therewith comprising an ignition mechanism, a plurality oftcurrent supply wires electrically connected to saidjgnitionrmechanism and having part thereof located between the sealed edges of the neck of the bulb andkthe'exhaust tube andanother part thereof located adjacent to a portion of the outer periphery of .tsaidneck, said neckof the bulb being provided with .tWo

flat, axial adapting surfaces, the distance between which is substantially equal to the distance between the two lead-in current supply wires.

3. An electric flash bulb having a glass base constituted by a substantially circular neck of the bulb and an exhaust tube -sealed: therewith comprising an ignition mechanism, a plurality of current-supply wires electrically connected to said ignition mechanism and having part thereof located betweenthe sealed edges of the neck of the bulb and the exhaust tube and another part thereof located adjacent to a portion of the outer periphery of said neck, said neck of the bulb being provided with at least one flat, axial surface, and a substantially curved surface which forms at theend remote from said bulb a substantially conical 'part provided with an aperture existing only before said exhaust tube is sealed to the neck o f theibulb said flat, axialsurface having boundary lines :on =said -30Ill621l portion which are substantially V-shaped with its apex at the edgeofsaidaperture.

ReferencesCited in'the file/of this patent UNITED STATES PATENTS 2,359,483 #Kuebler Oct. 3, 1944 9,699,659 :I-Iaas Jan. 18, 1955 

